1. Field of the Invention
The present invention relates to a process for the preparation of an olefins-containing mixture of hydrocarbons. The present invention further relates to a catalyst composition for the preparation of an olefins-containing mixture of hydrocarbons.
2. Description of the Prior Art
There is a considerable interest in the production of olefins since their reactivity renders them suitable for conversion to still further products. Ethylene and propylene are considered valuable starting materials for chemical processes, while C.sub.4 olefins can be used as a starting material for alkylation and/or oligomerization procedures in order to produce high octane gasoline and/or middle distillates. Isobutene can be usefully converted to methyl t-butyl ether.
It is know that hydrocarbonaceous feedstocks, such as light distillates, may be converted to products rich in lower olefins, especially ethylene and propylene, by high temperature steam cracking. The typical product obtained by such steam cracking is not entirely suited to the needs of the chemical industry though in that it results in a relatively high production of methane and a high ratio of ethylene to propylene.
Recently, alternative processes have been developed for the production of lower olefins from a wide range of hydrocarbonaceous feedstocks, for example, as described in European Patent No. 0347003, European Patent No. 0392590 and European Patent No. 0385538. Those processes have been found to give surprisingly high yields of lower olefins, low amounts of methane and a low ratio of ethylene to propylene and C.sub.4 olefins when compared with conventional steam cracking.
It has now been found that under comparative reaction conditions, very attractive product slates can be obtained in terms of both lower olefins and gasoline yields when use is made of a specific zeolitic catalyst.